Para tertiary butyl phenol is a stable and readily biodegradable chemical which is being widely used as an intermediate for phenol resins and polycarbonate resins. It is also used as a raw material for construction elements and floors in buildings.
Additionally, certain tert-butyl phenols are useful as fragrance or flavor compounds and may be used in a wide variety of household, personal care, and industrial items, such as perfumes, cleansers, or detergents. Conventional processes for producing tert.-butyl phenols from an isobutylene-containing C4 raffinate stream typically involve introducing methanol, or another alcohol, into the C4 stream to react and produce alkyl tertiary butyl ether intermediate that is further decomposed to make high-purity isobutylene, which can then be reacted with phenol to produce the t-butyl phenol. The additional step of adding methanol significantly increases the costs of producing t-butyl phenols and creates another undesirable byproduct. Besides the additional expense, the additional byproducts are unattractive for environmental reasons. Isobutylene may also be produced by isobutanol dehydration. However, in this case an impure product may form which, when used for alkylating phenols, leads to the formation of phenol by-products, such as derivatives having a secondary butyl substitute.
U.S. Pat. No. 4,532,368 discloses a process for the production of meta and para-alkylphenols from phenol and olefins in the presence of silicalites and ZSM-5 as catalyst at a temperature of 200° C. to 500° C.
U.S. Pat. No. 5,475,178 discloses a process for the alkylation of phenol with olefins using phosphotungsticacid supported on MCM-41 at a temperature range of 0° C. to 500° C. and at a pressure ranging from 0.2 to 250 atmospheres.
U.S. Pat. No. 5,399,786 discloses a process for the preparation p-tert butyl phenol by the reaction of phenol with alkyl tert-butyl ether in the presence of a protonated strong acid type catalyst in the temperature range of 60° C. to 130° C. and pressure ranging between atmospheric pressure to 5 kg/cm2.
U.S. Pat. No. 6,204,424 discloses a process for the alkylation of phenol with tert.-butyl ether and benzyl chloride in the presence of solid acid catalysts such as sulphated oxides of different metals such as Zr, Ti, Fe, Al, Sn and Bi.
Further, there have been proposed a process based on reaction of phenol with an isobutylene oligomer in the presence of Bronsted acid such as sulfuric acid, hydrofluoric acid, etc. and a process based on the reaction using ion exchange resins, etc. However, these prior art processes have certain disadvantages and have not been used as an industrial scale process. The use of Bronsted acids such as sulfuric acid, hydrofluoric acid, etc as catalysts causes serious corrosion problems at high temperature and it is difficult to carry out the reaction at a temperature higher than 120° C. When the reaction temperature is lowered, more by-products are produced and the yield of the desired 4-TBP is lowered. Furthermore, the use of these corrosive acids is undesirable from environmental points of view.
In the prior art process where ion exchange resins are used, there is neither corrosion of the reaction apparatus nor environmental pollution, but the reaction must be carried out at a reaction temperature of 110° C. or less, because the physical strength of the ion exchange resins is lowered at a high temperature and therefore, the yield of the desired 4-TBP is disadvantageously lowered.
Patent DD 87-311221 (Dec. 24, 1987) describes a process for the preparation of mono, bi-tri-tert-alkylated phenol derivatives using n-alkyl-tert-alkylethers. The process requires equimolar amounts of phenol and acid which generate corrosion problems due to high temperature.
U.S. Pat. No. 5,399,786 describes the preparation of tert.-butylphenols by the reaction of phenol with alkyl-tert-butyl ether instead of using pure isobutylene. The advantage of the process is mainly with the increased yield of the product from 88.7% (basic process) to 94.8%.
World patent (WO 2011069052 A3) disclosed a process for the production of various t-butyl phenols, such as 2,6-di-tert-butyl phenol and ortho-tert-butyl phenol, by selectively reacting phenol or a substituted phenol with an isobutylene-containing C4 raffinate stream.
A number of research papers have been published on the synthesis of alkyl phenol via alkylation of phenol. Samant and co-workers have reported (Appl. Catal. A, 2004, 276, 5) a liquid phase tert-butylation of phenol in the presence of k-10 clay and FeCl3/k-10 clay as catalysts. The process gave 100% conversion with 62.0% and 66.8% selectivity for p-tert-butylphenol respectively.
V. Hules reported (J. Catal, 2003, 218, 249) 52.7% conversion with 23.0% selectivity for p-tert-butylphenol using USY as catalyst, 54.2% conversion with 80.3% selectivity for p-tert-butylphenol using Zeolite-β, 28.8% conversion with 49.1% selectivity for p-tert-butylphenol using Mordenite, 12.6% conversion with 79.5% selectivity for p-tert-butylphenol using HZSM-5, and 31.5% conversion with 99.3% selectivity for p-tert-butylphenol using H-β as the solid acid catalyst in presence of ionic liquids such as [bmim]PF6, [omim]BF4 and [hmim]BF4.
Y. Shen and co-workers have reported (J. Mol. Catal. A 2004, 212, 301) 44.8% conversion with 49.0% selectivity for p-tert-butylphenol with tungstophosphoricacid supported onto MCM-41 as catalyst.
Of all the reactions described in the art, has certain drawbacks and provided lower yield of the desired p-tert. butyl phenol. The present invention has its advantages in using MTBE directly that provides insitu generation of isobutylene by cracking and providing more than 99% conversion with higher selectivity for p-tert butylphenol.